The firefly population appears to be decreasing in 13 countries, as reported in a 2010 report. Urban lights confuse the insects, leading to reduced reproduction, and increased use of pesticides of many types helps kill them off.
To get involved and report filefly sightings, go to Museum of Science, Firefly Watch. Fireflies can glow in yellow, orange, green, even blue!
See more at Firefly dot org.